Her daughter Nina Busby was on a bus, headed to school, when it drove up onto an island in the middle of a round-about, jolting the kids inside.

"They're saying their tummy hurt and their head hurt," Nina said.

Police say 15 kids between 5 and 10 years old were taken to local hospitals.

"For precautionary reasons, there are no serious injuries, we just wanted to make sure everybody was OK," California Highway Patrol Sgt. Reginald Gayles said.

The students were physically OK, but they were badly shaken up after the accident.

"They were so terrified they said I'm not getting back on that bus, so they started just walking up saying I'm gonna walk to school," Nina said. "And the bus driver was saying come back come back."

The scene of the crash is incredibly almost three quarters of a mile from where police found the children. Police say the kids took off down the street on their own and kept going until a local security guard stopped them.

"I believe the protocol is they're not supposed to even get off the bus at all. So, the children were so scared that they were just getting off the bus," Busby said.

And that's why it took so long for her to find her daughter. The school district was still trying to reach some parents hours later.

"To let them know where their children are and whether there's any injuries," San Francisco School District spokesperson Heidi Anderson said.

As for the driver, police say he was trying to go around a stopped vehicle when he went into the roundabout, but ran up onto the island with the back left wheel. There was no damage to the bus.

"Obviously we're checking into the background of the school bus driver, make sure he has his credentials all in order," Gayles said.

Police say he was not under the influence of drugs or alcohol, but Busby does wish he had remained calm and kept his cool.

"He was just panicked, but he was kind of cursing at the kids and yelling at them and they were really scared, you know?" Busby said.

A supervisor for the first student bus company declined to comment as he drove the bus away.